Color image processing method and apparatus

ABSTRACT

A color image processing method comprising the steps of extracting a particular color signal of three color image signal components from an input color image signal; converting the particular color to another designated color; designating the particular color and the designated color; and forming a color image on the basis of the converted color image signal.

This application is a continuation, of application Ser. No. 084,012filed Aug. 11, 1987 now abandoned.

FIELD OF THE INVENTION

This invention relates to a color image processing method and apparatuswhich processes a color image signal to form a color image.

BACKGROUND OF THE INVENTION

Color image recording apparatus that record color image informationusing a recording method such as ink jet, heat transfer orelectrophotography are well known.

FIG. 2 is a block diagram for processing a signal in a color imagerecording apparatus of this type. An image reader or an image datastorage, not shown, outputs three color image signals 1a, 1b and 1cindicative of yellow, magenta and cyan, respectively, which are input toa color correction unit 2 which performs a color correction such asmasking on these input signals. A gradation correction unit 3 performs agradation correction on the corrected color signals from colorcorrection unit 2. A printer 4 forms yellow, magenta and cyan images inaccordance with the corrected gradation signals and records a colorimage.

An apparatus of this type is most desired to reproduce a color faithfulto that of an input image. In some cases, it may be desired to output animage by changing a color of the input image. For example, in the designof a poster, it may be desired to reproduce an original image in variouscolors. Especially, it is strongly desired to change only a particularcolor portion of the original image to another color to output theresulting image.

U.S. Pat. No. 4,204,728 discloses an electronic color photographyreproduction apparatus (color electrophotographic copying apparatus)which focuses an optical image passing through R-, G- and B- filtersonto a photosensitive medium and develops the same using developers ofcyan, magenta and yellow. In such related art, however, not only theparticular color in the original image but also other colors containingthe color components (Y, M, C) contained in the particular color may bechanged. Even in a color image recording apparatus which temporarilychanges a color image into color component signals and records thecolors, if colors not corresponding to three color (yellow, magenta andcyan) signals are printed with the yellow, magenta and cyan colorsignals, an image different in color from the input image can beproduced. For example, if magenta, cyan and yellow are printed withyellow, magenta and cyan signals, respectively, the red portion ofyellow+magenta, the blue portion of magenta+cyan and the green portionof cyan+yellow will be reproduced with the blue of magenta+cyan+Yellowwill be reproduced with the blue of magenta+cyan, the green ofcyan+yellow, and the red portion of yellow+magenta, respectively.However, according to such method, all colors of the input image exceptfor three monochromatic elements, yellow, magenta and cyan, will bereproduced in different colors from those of the original image, so thatit is impossible to replace only a particular color with another.

U.S. Pat. No. 4,538,182 discloses a color reproduction apparatus whichreproduces a plurality of particular colors, for example, two colors(red and black) or three colors (red, blue and black), in which theoriginal red will be changed to black or the original black will bechanged to red. However, it is impossible to change a delicate colorincluding a plurality of color components to another or to change acolor to a plurality of delicate color components.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a color image processingmethod and apparatus which eliminates the aforementioned prior artdrawbacks.

It is another object of this invention to provide a color imageprocessing method and apparatus which can replace only a selectedparticular color portion in an input color image signal with a desireddesignated color.

It is still another object of this invention to provide a color imageprocessing method and apparatus which can read a predetermined originalcolor, store the value of signals representing the color components ofthe predetermined color, and replace the color component signalscorresponding to the stored signal values with desired designatedcolors.

These and other objects of this invention will be apparent from thefollowing description when taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a signal block diagram of the inventive embodiment;

FIG. 2 is a signal block diagram of a related art.

FIG. 3 is a block diagram showing the basic structure of a secondembodiment of this invention; and

FIG. 4 is a block diagram showing the circuit structure of the secondembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A first embodiment of this invention will now be described withreference to the drawings.

FIG. 1 is a signal processing block diagram of the embodiment. Likereference numerals denote like elements or parts in FIGS. 1 and 2.

Three 6-bit color signals 1a, 1b and 1c indicative of yellow, magentaand cyan, respectively, are input to a selector 5 via a color correctionunit 2 and a gradation correction unit 3. Signals 1a-1c are divided by16 at dividing ROMs 6a, 6band 6c to be converted to 4-bit signals 7a, 7band 7c, respectively. Namely, if a color represented by three colorsignals is represented by (Y, M, C), there are a total of 64³ =262144colors (0, 0, 0) - (63, 63, 63) represented by 1a-1c, and there are atotal of 16³ =4096 converted colors (0, 0, 0) - (15, 15, 15),represented by 7a-7c.

A switch SW1 selects a color in the input image to be replaced withanother and can one among 24 colors herein. Terminals 8-1 to 8-24 areeach given 12-bit data corresponding to a separate one of 24 colors sothat the user can select a desired color freely among them. Each 12-bitdata corresponding to a separate one of the 24 colors is determined inadvance as follows.

For example, assume that the user selects orange and connects switch SW1to terminal 8-2. If a combination of signals 7a-7c representing orangeis, for example, (5, 6, 2), a 12-bit signal ##STR1## corresponding (5,6, 2) is output from terminal 8-2.

In this way, 12-bit signals are determined corresponding to respectivecolors and stored in a ROM, not shown, and applied to the correspondingterminals.

A signal 9 selected by SW1 among such 12-bit signals is input to acoincidence detection unit 10 which also receives signals 7a-7c afterthe division. Coincidence detection unit 10 includes an Exclusive-Orgate which compares 12 bits of signal 9 and 12 bits (4×3) of signals7a-7c on a bit-by-bit basis to output a signal 11 which will become highwhen all these compared bits coincide and will become low otherwise.

Switch SW2 selects which color a particular color of the original imageshould be changed to. To this end, there are also 24 colors preparedherein. Terminals 12-1 to 12-24 are given different 4-bit data outputs,the number of bits of which is determined in accordance with the numberof colors selectable.

The signal 12 selected by SW2 is input as address data to ROMs 13a-13c.Printer drive signals necessary for outputting the selected color arestored in the corresponding ROMs. For example, assume that a color bereplaced and printed with green. In order to print this green, whenthree color signals to be input to the printer are (40, 20, 50) (assumethat each color is one of 64 gradations 0-63), the ROM outputs 14a-14cobtained when green is selected by SW2 are set so that 14a, 14b and 14care 40, 20, 50, respectively. In this way, three color drive signalscorresponding to each color are stored in ROMs 13a-13c.

The respective ROM outputs 14a-14c are input to selector 5 together withthe respective outputs 15a-15c of gradation correction unit 3. Selector5 produces at its outputs 16a-16c signals 15a-15c when signal 11 is lowand signals 14a-14c when signal 11 is high.

Selector outputs 16a-16c are input to printer 4 which forms yellow,magenta and cyan images in accordance with these signals and records acolor image.

Description will now be made of the case in which such apparatusreplaces only orange color of an input image with green and outputs theresultant image.

The user sets SW1 to orange and SW2 to green. As described above, signal9 is 010101100010, and signal 12 is a 5-bit signal corresponding togreen. If an input image is not orange, signals 7a-7c will not coincidewith signal 9, so that the output 11 of coincidence detection unit 10becomes low. Therefore, selector 5 outputs, as outputs 16a-16c, signals15a-15c processed in a normal manner which outputs are supplied to theprinter to thereby perform printing.

If the input image becomes orange, signals 7a-7c will coincide withsignal 9 and the output 11 of coincidence detection unit 10 becomeshigh. Selector 5 then supplies outputs 14a-14c of ROMs 13a-13c toprinter 4 to print green.

In this way, an image can be output in which only orange of the inputimage is replaced with green. By freely changing SW1 and SW2, the colorof an image portion to be replaced and a color to be printed thereforcan be selected freely.

While in the above embodiment, dividing ROMs 6a-6c which dividecorresponding 6-bit signals by 16 to output 4-bit signals are used, onlythe 4 most significant bits of the 6-bit signals may be extracted.Alternatively, any means may be used which compresses the 6-bit signalsto corresponding ones of bits fewer than 5.

Instead of a logic element such as an Exclusive-Or gate, the coincidencedetection unit may be a ROM which receives signal 9 as the mostsignificant address bits, signals 7a-7c as the least significant addressbits, stores 1 at addresses where the most and least significant bitsare equal, 0 at addresses otherwise, and outputs the stored value as asignal 11.

So long as printer 4 can form a color image in accordance with signals16a-16c, it may be any of ink jet, heat transfer and electronicphotography types.

While in the above embodiment the printer has been described ascombining three colors yellow, magenta and cyan to form a color image,it may combine four or more colors which include black in addition tothose three colors. Otherwise, it may be of the type which combines twocolors such as red and black.

While in the above embodiment the kind of colors to be replaced and thekind of colors therefor to be printed are each shown as being 24 colors,they are not limited to them and any kinds of colors may be prepared.

Especially, if white and black are included in these colors, thefollowing advantages will be obtained.

If white is included in colors to be replaced, for example, outputimages with various colors in their backgrounds can be obtained from theoriginal picture with no colored background. If black is included,output images can be obtained which have characters of various colorsfrom the original picture with black characters.

If white is included in colors to be printed, a picture can be outputwith no print in a portion corresponding to the original particularcolor portion and the no-print portion can be conveniently coated laterwith a color such as gold or silver which cannot be expressed by theprinter. If black is included, it will be convenient to reverse thenegative and positive of a white and black image.

As described above, according to this embodiment, when 3 combined inputcolor image signals become predetermined values, predetermined colorsignals are output to the printer to output an image in which only anyparticular portion of the input image is replaced with any designatedcolor.

A second embodiment of this invention will now be described. It includesimage input means for providing an image to be recorded, in acombination of color signals, replaced-color input means for providingin a combination of color signals, a designated replaced color of theimage to be recorded, memory means for storing the combination of colorsignals supplied by the replaced color input means, comparison means forcomparing the combination of color signals read out of the memory meansand the combination of color signals supplied by the image input meansto output a signal representing a coincidence when both the combinationscoincide, output color designation means for designating an output colorsubstituted for the replaced color in a combination of color signals,signal selection means for selectively outputting a color signal fromthe image input means or a color signal from the output colordesignation means in accordance with the output from the comparisonmeans, and image output means for forming an image of a plurality ofcolors in accordance with the output of the signal selection means.

Colors of an origianl document to be replaced are read and stored inadvance. When signals indicative of the stored colors do not coincidewith three color input image signals, an input image signal subjected toregular color and gradation correction is output to the recording unitwhile when they coincide, the previously selected color signal is outputto the recording unit. Therefore, an image in which only a particularcolor portion of the input image is replaced with another particularcolor can be output to a recording medium.

Now, the second embodiment of this invention will now be described inmore detail with reference to FIGS. 3-4.

FIG. 3 shows the basic structure of the second embodiment which includesimage input means a for providing an image to be recorded, in acombination of color signals, replaced-color input means b forproviding, in a combination of color signals, a designated replacedcolor of the image to be recorded, memory means c for storing thecombination of color signals supplied by the replaced-color input means,comparison means d for comparing the combination of color signals readout of the memory means c and the combination of color signals suppliedby the image input means a to output a signal representing a coincidencewhen both the combinations coincide, output color designation means efor designating an output color substituted for the replaced color in acombination of color signals, signal selection means f for selectivelyoutputting a color signal from the image input means a or a color signalfrom the output color designation means e in accordance with the outputfrom the comparison means, and image output means such as a colorprinter g for forming an image of a plurality of colors in accordancewith the output of the signal selection means f.

FIG. 4 shows the circuit structure of the second embodiment. In FIGS. 1and 4, like reference numeral denote like components.

In FIG. 4, a read unit 105 reads a color image in an original document,a color film or the like, using an image sensor such as a CCD (chargecoupled device) provided therein and outputs it as three color signalsof Y. M. C. respectively, shown by 1a , 1b, 1c. Dividing ROMs (read onlymemories) 106a, 106b, 106c divides, by 16,6-bit color signals 1a , 1b,1c, namely, converts same to corresponding 4-bit signals. Three switchesSW11, SW21 and SW31, ganged as a unit, select a destination to whichoutput signals 107a, 107b, 107c from ROMs 106a, 106b, 106c, areconnected to designate color to be changed. A RAM (random access memory)109 temporarily stores signals 107a, 107b, 107c selectively suppliedfrom dividing ROMs 106a-106c via corresponding switches SW11-SW31.Coincidence detection unit 110 compares the signals read from RAM 109with the signals, as they are, supplied from dividing ROMs 106 a-106c tooutput a coincidence signal 116 when coincidence holds. An operationswitch SW41 designates a color to be recorded among, for example, 24colors, after color substitution. ROMs 113a, 113b, 113c output threecorresponding combined color signals 114a-114c corresponding to adesignated color by switch SW41. The selection means including aselector 115 outputs to printer 4 the signals 114a, 114b, 114c from ROMs113a, 113b, 113c when it receives a high or coincidence signal 116 fromcoincidence detection unit 110 and outputs signals 115a, 115b, 115c ofgradation correction unit 3 when it receives no coincidence signal.

In operation, in a color designation mode (1) the user causes read unit105 to read only a color portion to be replaced in an original document.Three 6-bit color (yellow, magenta and cyan) signals 1a-1c representingthe color components of the read color are divided by 16 at dividingROMs 106a-106c to be converted to 4-bit signals 7a-7c. Namely, if acolor to be represented by three color signals is (Y, M, C), there are atotal of 64³ =262144 colors (0, 0, 0) - (63, 63, 63), shown by 1a-1c inthe decimal notation, and there are a total of 16³ =4096 colors (0, 0,0) - (15, 15, 15) represented by signals 107a-107c after conversion bydividing ROMs 106a, 106c.

In the color designation mode (1), switches SW11, SW21, SW31 areconnected to contacts 108a, 108b, 108c and a total of 12 data bitsrepresented by signals 107a-107c from ROMs 106a-106c are stored in RAM109.

In the color designation mode (2), the user selects, by switch SW41, anoutput color to replace the original color. Namely, this switch SW41selects that output color among 24 colors prepared in advance. Switchterminals 111-1 to 111-24 output different 4-bit data, the number ofbits of which is determined in accordance with the number of colors tobe selected.

A 4-bit signal 112 selected by switch SW41 is input as address data toROMs 113a, 113b, 113c which store printer drive signals necessary foroutputting the selected color.

For example, assume that the replaced color portion be printed withgreen. In order to print this green, when three color signals to beinput to printer 4 are (40, 20, 50), each color being one of 64gradations 0-63, data is stored in advance in ROMs 113a, 113b, 113c sothat the outputs 114a, 114b, 114c of ROMs 113a, 113b, 113c obtained whengreen is selected by SW41 are "40", "20", "50", respectively.

In this way, three color drive signals corresponding to a respective oneof colors are stored in ROMs 113a-113c and outputs 114a-114ccorresponding to selective signal 112 form switch SW41 are input toselector 115.

When a print start button, not shown, is pressed to enter a print mode,the original document is read by read unit 105 and three color signals115a-115c corrected normally with respect to color and gradation bycolor and gradation correction units 2 and 3 are input to selector 115.

On the other hand, since in the print mode the ganged switches SW11,SW21, SW31 are connected to contacts 108d, 108e, 108f, respectively, thedata read from the document and divided at ROMs 106a-106c are inputunchanged as 107a-107c to coincidence detection unit 110. At the sametime, the data on a color to be replaced and read already in the colorselective mode (1) is read from RAM 109 to be compared with the documentdata 107a-107c. Coincidence detection circuit 110 compares signals fromRAM 109 and signals 107a-107c from the document on a bit-by-bit basis,using its internal Exclusive-Or gate, not shown, which outputs toselector 115 a coincidence signal 116 which becomes high when all thecompared bits coincide and low otherwise.

Selector 115 outputs to printer 4 the signals 114a-114c from ROMs113a-113c when signal 116 is high and outputs to printer 4 the signals115a-115c from gradation correction unit 3 when the coincidence signal116 is low.

These signals 116a-116c output from selector 115 are input to colorprinter 4 which may be an ink jet printer, a heat transfer printer of anelectronic photography printer to reproduce a full color image printedin yellow, magenta and cyan.

As a result, when the color of the document read in the print mode doesnot coincide with the color read in the color designation mode (1) andstored in RAM 109, an image formation is performed using signalssubjected to normal color and gradation corrections while when theycoincide, an image containing the color designated in the colordesignation mode (2) is printed. In this way, only a particular colorportion in the document read in the color designation mode (1) can bereplaced by a desired color designated in the color designation mode (2)and output.

While in the above embodiment, the dividing ROMs 106a-106c which divide6-bit signals by 16 and outputs 4-bit signals are used, only the mostsignificant 4 bits of each of the 6-bit signals may be output.Alternatively, any means which can compress 6-bit signals to ones ofbits fewer than 5 may be used.

If the input image signals as they are should be input to RAM 109without compression, possible slight changes in the input signals wouldprevent part of a color designated to be replaced from being replaced,so that it may be desirable to perform an appropriate compression.

Instead of using a logic device such as an Exclusive-Or gate, thecoincidence detection unit 110 of FIG. 4 may include a ROM in which thesignals from RAM 109 are input to the most significant address bits andthe signals from original document are input to the least significantaddress bits, "1" is stored in advance to addresses where the most andleast significant bits are equal, "0" is stored in advance in addresseswhere the most and least significant bits are not equal, and data "1" or"0" is output as a signal 116 to selector 115.

While in this embodiment the printer 4 has been described as combiningthree colors yellow, magenta and cyan to form a color image, it maycombine four or more colors which include black in addition to thosethree colors. Otherwise, it may be of the type which combines two colorssuch as red and black.

While in the above embodiment the kind of colors which can be selectedin the color designation mode (2) is shown as 24 colors, it is notintended in a limitative sense and any kinds of colors may be prepared.Especially, if white and black are included in these colors, thefollowing advantages will be obtained. For example, if white is includedin colors to be printed, a picture can be output with no print in aportion corresponding to the original particular color portion and theno-print portion can be conveniently coated later with a color such asgold or silver which cannot be expressed by the printer. If black isincluded, it will be convenient to reverse the negative and positive ofa white and black image.

As described above, according to the second embodiment of thisinvention, a color portion to be replaced in the original document isread and stored in advance. When the stored color signals do notcoincide with three color input image signals, the input image signalssubjected to regular color and gradation corrections are output to therecord unit while when they coincide, the color signals selected inadvance are output to the record unit. Therefore, an image in which aparticular color portion in the image is replaced with anotherdesignated color can be output to a recording medium.

This invention is not limited to the first and second embodimentsdescribed above and may be applied and modified in various forms withoutdeparting from the scope of the attached claims.

We claim:
 1. A method for processing a color image including a pluralityof colors to replace one particular color of the color image with asecond color, comprising the steps of:designating one particular colorof a color image and a second color, said one particular color having aplurality of color components; inputting a color image signal;extracting said one particular color from the input color image signal;converting said one particular color to said second color; and forming acolor image on the basis of the converted color image signal.
 2. Themethod of claim 1, further including the step of:selecting betweenoutputting a color image signal indicative of the second color andoutputting a signal corresponding to the input color image signal. 3.The method of claim 2, further including the step of:correcting thecolor of the input color image signal.
 4. A method for processing acolor image signal to replace one particular color of the color imagesignal with a second color, comprising the steps of:designating oneparticular color of a color image and a second color; inputting a colorimage signal including a plurality of color component signals;extracting said one particular color from the input color image signal;converting said one particular color to said second color, said secondcolor including a plurality of color image signal components; andforming a color image based on the color image signal converted by theconverting step.
 5. The method of claim 4, further including the stepof:selecting between outputting a color image signal indicative of thesecond color and outputting a signal corresponding to the input colorimage signal.
 6. The method of claim 5, further including the stepof:correcting the color of the input color image signal.
 7. A colorimage processing apparatus comprising:input means for providing a colorimage signal corresponding to an original image; memory means forstoring a color image signal including a plurality of color componentsignals corresponding to a predetermined portion of the original image;means for determining whether the color image signal stored in saidmemory means corresponds to the input color image signal from said inputmeans; means for designating a second color, to be substituted for thecolor image signal in said memory means; means for selectivelyoutputting one of the input color image signal from said input means anda color image signal corresponding to the second color in accordancewith an output from said determining means; and means for forming acolor image of a plurality of colors in accordance with the output fromsaid outputting means.
 8. The apparatus of claim 7, wherein said inputmeans reads an original document and outputs a color image signal of aplurality of color components.
 9. The apparatus of claim 7, wherein theinput color image signal includes a plurality of n bits and wherein saiddetermining means performs the determination using a converted colorimage signal of bits fewer than n.
 10. The apparatus of claim 7, furtherincluding:means for correcting the color of the input color imagesignal.
 11. The method of claim 1, wherein the color image signalincludes a plurality of n bits, and wherein the extracting step includesextracting one particular color on the basis of a converted color imagesignal of bits fewer than n.
 12. The method of claim 4, wherein theinput color image signal includes a plurality of n bits, and wherein theextracting step includes extracting one particular color on the basis ofa converted color image signal of bits fewer than n.
 13. A color imagesignal processing apparatus comprising:means for inputting a color imagesignal, the color image signal including a plurality of color componentsignals; means for sorting a specific color and a second color; meansfor comparing the color image input by said inputting means with thespecific color set by said setting means; and means for converting thecolor image signal input by said inputting means into the second color,in accordance with the result of comparison performed by said comparingmeans.
 14. A color image signal processing apparatus according to claim13, wherein said inputting means comprising means for reading anoriginal document.
 15. A color image signal processing apparatusaccording to claim 13, wherein the color image signal input by saidinputting means includes a plurality of n bits, and said comparing meansperforms the comparison using the converted color image signal of bitsfewer than n.